Experimental Investigation of Nano Silica on Wettability Alteration and Enhanced Oil Recovery from Carbonate Reservoir Using Low Salinity Water

As oil fields approach to the end of the primary production phase, the new technologies should be employed to increase the recovery of hydrocarbons. In recent decades, nanofluid has been proposed as an efficient, and environmentally friendly approaches for EOR purpose. The target of this study is to investigate the effect of silica nanoparticle on the wettability alteration of the carbonate rock. In this study, four different concentrations of silica nanoparticle were used (0.01, 0.02, 0.05, and 0.1 wt.%) in low salinity seawater (1000 ppm of positive ions). The stability of nano particle in brine is one of the challenge while using for EOR. In this study the stability of nano fluid was achieved without using any surfactant. The Spontaneous imbibition experiments, and contact angle measurements were carried out at 75 °C to check the performance of nano fluids in wettability alteration of carbonate rock. The results showed that the silica nanoparticle has a significant effect on the oil recovery from carbonate rock. The diluted sea water (1000 ppm) without nano particle resulted to the oil recovery of 10.45% whereas nano fluid with concentration of  0.01, 0.02, and 0.05 wt.%  resulted to the oil recovery of 11.5%, 10.83%, and 22.16% , respectively. The contact angle results also confirmed that the silica nanoparticle has a positive effect on the wettability alteration of the carbonate rock surface toward water wetness. The permeability measurement after and before spontaneous imbibition tests showed that the pores were not blocked due to nano particle precipitation. The impact of initial water in the rock was investigated on the performance of wettability alteration while using nano fluid. The results depicted that the presence of initial water in the carbonate rock adversely affect the oil production.